Forage length, milk yields and reticular pH
By Francesca Harding
A recent study by Harper Adams University used eCow boluses to investigate the impact of grass silage chop-lengths on herd health in the UK. Funded by AHDB-Dairy, researchers examined the impact of feeding short or long chop ryegrass silage, as well as the result of adding maize silage. Scientists explored the effects of each diet of performance, reticular pH, metabolism, and eating behaviour.
The chop length of forage can have a substantial impact on dairy cow performance. If the chop length is too short then this can result in digestion problems, but too long may reduce feeding and production. Therefore, finding a balance is key to maintaining both the health and productivity of the herd.
Each group of cows was allocated one of four diets consisting of short or long chop-length grass silage, either with or without maize silage. The herd was closely monitored to explore the impact of each diet on various parameters including reticular pH, and milk production.
Figure 1 – Feeding forage of a longer chop length can increase milk production without significantly altering the reticulum pH.
Using eCow boluses, researchers were able to continually monitor the dynamics of the reticulum pH. In this study, it was found that the grass chop length does not significantly alter the reticulum pH. However, it was noted that the chop length did have an impact on milk production, with cows fed shorter lengths producing more milk than those fed longer lengths.
When maize silage was added to the diet, both milk production and milk protein content increased. However, including maize silage into the diet also resulted in a lower reticulum pH. Although the reticulum pH did not decrease to below the SARA threshold, it is highlights that even small changes in diet can have an impact on the reticulum and the digestive system as a whole.
The eCow bolus can be used as a research tool, but can also be used as a diagnostic tool for both veterinarians and farmers. By providing continual and accurate measurement of reticulum pH, the eCow bolus can be used altering a herd’s diet to monitor changes to reticulum pH and temperature.
As shown in this study, dietary alterations can cause changes to reticulo-rumen pH, and in some cases this can lead to SARA. These changes may initially be asymptomatic, however using the eCow bolus any increase to the SARA risk can be detected early. Early detection and intervention is key, and will ensure that there is no long term damage to the digestive system.
More information on this study can be read here.
Tayyab, U., Wilkinson, R. G., Charlton, G. L., Reynolds, C. K., Sinclair, L. A. (2018) Grass silage particle size when fed with or without maize silage alters performance, reticular pH and metabolism of Holstein-Friesian diary cows. Animal, 9: 1-9.